1. Field of the Invention
The current invention relates to a method for measuring the injection quantity of injection systems, in particular for motor vehicles and in particular in production testing, in which a testing fluid is injected into a measuring chamber by an injection system and the injection-induced movement of a piston, which at least partially defines the measuring chamber, is detected by a detection device, which transmits a measurement signal.
2. Description of the Prior Art
A method of the above kind is known from the market. The method is applied by using a device, which is referred to as an injected fuel quantity indicator. This component is comprised of a housing in which a piston is guided. The inner chamber of the housing and the piston define a measuring chamber. This measuring chamber has an opening against which an injection system, for example an injector with an injection nozzle, can be placed in a pressure-tight manner. When the injection system injects fuel into the measuring chamber, a fluid contained in the measuring chamber is displaced. This causes the piston to move, which is detected by a distance sensor. The volume change of the measuring chamber and of the fluid contained therein and therefore the quantity of fuel injected can be calculated from the distance traveled by the piston.
In the known injected fuel quantity indicator, a device comprised of a measuring plunger and an inductive distance measuring system is used to measure the movement of the piston. The measuring plunger is embodied as a probe or is connected to the piston. When the piston moves, this also causes the measuring plunger to move and finally, the movement of the measuring plunger is detected and a corresponding signal is sent to an evaluation unit.
The known method already operates with a very high degree of precision with regard to the detected movement of the measuring plunger. However, the mass of the injected testing fluid calculated from this movement and the volume of injected fuel likewise calculated from it fall somewhat below the path measurement in terms of the precision. This problem is more intense the smaller the movement of the piston is, i.e. the smaller the injected testing fluid quantity is. But it is precisely these small quantities of testing fluid that current and future injection nozzles must be able to reliably inject.
The object of the current invention, therefore, is to modify a method of the type mentioned at the beginning so that it permits a more precise determination of the mass of the injected testing fluid and of the volume of testing fluid injected.
This object is attained in that the pressure of the testing fluid is detected in the measuring chamber and the measurement signal is processed taking into account the pressure detected.